Hasil untuk "Chemical industries"

C. Lin, Lucie A. Pfaltzgraff, Lorenzo Herrero-Davila et al.

Anna Trakoli

D. Huh, G. Hamilton, D. Ingber

I. Siró, D. Plackett

F. Cherubini

J. Bozell, G. Petersen

P. Kadlec, Bogdan Gabrys, S. Strandt

P. Duxson, J. Provis, G. C. Lukey et al.

D. Formenti, F. Ferretti, F. Scharnagl et al.

The reduction of nitro compounds to the corresponding amines is one of the most utilized catalytic processes in the fine and bulk chemical industry. The latest development of catalysts with cheap metals like Fe, Co, Ni, and Cu has led to their tremendous achievements over the last years prompting their greater application as "standard" catalysts. In this review, we will comprehensively discuss the use of homogeneous and heterogeneous catalysts based on non-noble 3d-metals for the reduction of nitro compounds using various reductants. The different systems will be revised considering both the catalytic performances and synthetic aspects highlighting also their advantages and disadvantages.

C. Kappe

Cheng Tang, Yao Zheng, M. Jaroniec et al.

Compared to modern fossil fuel-based industrial refineries, the emerging electrocatalytic refinery (e-refinery) is a more sustainable and environmentally benign strategy to convert renewable feedstocks and energy sources to transportable fuels and value-added chemicals. E-refinery will promisingly lead to defossilization, decarbonization, and decentralization of chemical industry. A crucial step in conducting e-refinery processes is the selection and development of appropriate reactions and optimal electrocatalysts for efficient cleavage and formation of chemical bonds between H, O, C, and N. However, compared to well-studied primary reactions (e.g., O 2 reduction, water splitting), the mechanistic aspects and materials design for emerging complex reactions are yet to be settled. To address this challenge, herein, we first present concise and comprehensive fundamentals of heterogeneous electrocatalysis and some primary reactions, and then implement these foundations to establish the framework of e-refinery with greater complexity by electrocatalytic coupling in situ generated intermediates (integrated reactions) or products (tandem reactions). We will also present a set of materials design principles and strategies to efficiently manipulate the reaction intermediates and pathways, and conclude with a perspective section to accelerate the development of feasible electrochemical industrial processes.

R. Nisticò

Abstract Polyethylene terephthalate (PET) is the third most widely diffused polymer exploited in the packaging industry, monopolizing the bottles market for beverages, and covering almost the 16% of the European plastic consumption in the packaging industry. Even if PET primarily derived from fossil sources and remains not-biodegradable in the environment, novel advancements in the field pointed out the possibility of producing PET in a more sustainable way (e.g., from biomasses) or the possibility of biodegrade this polyester through the enzymatic action of specific genetically-modified/isolated bacteria/enzymes. By considering also the high recyclability of PET, and the possibility of potentially indefinitely re-use this material, one can assume that the future of PET is still to be written. Therefore, all aspects involving the industrial production (with traditional and sustainable chemical routes), intrinsic physicochemical/thermal/mechanical properties, undesired degradation phenomena, chemical/mechanical recycling processes, and processability of PET are here critically discussed. A particular emphasis has been dedicated to the role of PET in the packaging industry. The main achievements in the PET processing for food packaging are presented, analyzing advantages and disadvantages of each technology. This document aims at providing a useful instrument that collects past, present, and future of the PET: a well-consolidated material that has been able to renew itself over time.

Laura Buglioni, Fabian Raymenants, Aidan Slattery et al.

Photoinduced chemical transformations have received in recent years a tremendous amount of attention, providing a plethora of opportunities to synthetic organic chemists. However, performing a photochemical transformation can be quite a challenge because of various issues related to the delivery of photons. These challenges have barred the widespread adoption of photochemical steps in the chemical industry. However, in the past decade, several technological innovations have led to more reproducible, selective, and scalable photoinduced reactions. Herein, we provide a comprehensive overview of these exciting technological advances, including flow chemistry, high-throughput experimentation, reactor design and scale-up, and the combination of photo- and electro-chemistry.

Alessia Tropea

The rapid growth of the global population and the impending depletion of fossil fuels, currently meeting approximately 80% of the world’s power needs, have intensified interest in biofuels derived from renewable biomass. This editorial refers to the Special Issue, “Biofuel Production and Processing Technology, 3rd Edition,” which highlights the transition of fermentation-based technologies from isolated processes into integrated, multifunctional biorefinery platforms. The collection includes nine contributions (eight original articles and one review) covering diverse advancements, including: The valorization of industrial intermediates, strategies to improve anaerobic digestion through co-digestion and heat recovery integration, mechanistic insights into syngas fermentation and the development of multi-product microbial systems, emerging frontier technologies, such as biological hydrogen production in depleted oil and gas reservoirs. Collectively, these studies emphasize that the future of sustainable energy relies on system-level optimization, balancing feedstock flexibility, energy integration, and environmental performance within a circular bioeconomy.

Qi You, Yan Sun, Feng Wang et al.

Understanding the solvation structure of electrolytes is critical for optimizing the electrochemical performance of rechargeable batteries, as it directly influences properties such as ionic conductivity, viscosity, and electrochemical stability. The highly complex structures and strong interactions in high-concentration electrolytes make accurate modeling and interpretation of their ``structure-property" relationships even more challenging with spectroscopic methods. In this study, we present a machine learning-based approach to predict dynamic $^7$Li NMR chemical shifts in LiFSI/DME electrolyte solutions. Additionally, we provide a comprehensive structural analysis to interpret the observed chemical shift behavior in our experiments, particularly the abrupt changes in $^7$Li chemical shifts at high concentrations. Using advanced modeling techniques, we quantitatively establish the relationship between molecular structure and NMR spectra, offering critical insights into solvation structure assignments. Our findings reveal the coexistence of two competing local solvation structures that shift in dominance as electrolyte concentration approaches the concentrated limit, leading to anomalous reverse of $^7$Li NMR chemical shift in our experiment. This work provides a detailed molecular-level understanding of the intricate solvation structures probed by NMR spectroscopy, leading the way for enhanced electrolyte design.

Ayşegül Gültekin Toroslu

Alumina-based insulators are widely used in regions with extreme temperature fluctuations, such as polar areas, due to their high mechanical strength, low thermal expansion, and excellent electrical insulation properties. To improve the reliability of electrical transmission lines in such environments, a detailed understanding of their structural and physical characteristics is needed. This study investigates the mechanical and microstructural properties of high-strength alumina-based insulators using X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDAX). The manufacturing process is analyzed, focusing on density, porosity, and phase structure validation. The results show that increased mullite formation within the insulator structure improves mechanical strength, especially with low porosity (10.8%), having homogeneous size distribution and high density (2.73 g/cm3). Strength tests indicate that the produced insulators resist forces up to 14 kN. Among the samples, those produced using alumina powder show better mechanical strength and reliability, likely due to more controlled mullite formation and reduced impurity content. As a result, an improved production process for reliable alumina-based C12.5-650 insulators was produced. These findings provide valuable insights for significantly improving the production of alumina-based insulators for harsh environments. Resumen: Los aisladores a base de alúmina se utilizan ampliamente en regiones con fluctuaciones extremas de temperatura, como las zonas polares, debido a su alta resistencia mecánica, baja expansión térmica y excelentes propiedades de aislamiento eléctrico. Para mejorar la fiabilidad de las líneas de transmisión eléctrica en dichos entornos, es necesario comprender detalladamente sus características estructurales y físicas. Este estudio investiga las propiedades mecánicas y microestructurales de aisladores a base de alúmina de alta resistencia mediante difracción de rayos X (DRX) y microscopía electrónica de barrido con análisis de rayos X por dispersión de energía (SEM-EDAX). Se analiza el proceso de fabricación, centrándose en la densidad, la porosidad y la validación de la estructura de fases. Los resultados muestran que una mayor formación de mullita en la estructura de alúmina mejora la resistencia mecánica, especialmente con una baja porosidad (10,8%), una distribución de tamaño homogénea y una alta densidad (2,27 g/cm3). Las pruebas de resistencia indican que los aisladores producidos resisten fuerzas de hasta 14 kN. Entre las muestras, las producidas con polvo de alúmina de alta pureza presentan mayor resistencia mecánica y fiabilidad, probablemente debido a una formación más controlada de mullita y a un menor contenido de impurezas. Como resultado, se desarrolló un proceso de producción mejorado para aisladores C12.5-650 fiables a base de alúmina. El proceso produjo aisladores con una porosidad del 10,8%, una densidad de 2,27 g/cm3 y un rendimiento mecánico superior al de los tipos tradicionales C8-650. Estos hallazgos aportan información valiosa para mejorar significativamente la producción de aisladores a base de alúmina para entornos hostiles.

Dariia Chernomorets, Alex Sangiorgi, Jan Hostaša

In this work, transparent Y2O3 ceramics were obtained by direct ink writing (DIW) followed by vacuum sintering at 1720°C for 32 h. The optimal ink composition was identified as 78 wt.% of solid loading, 1.5 wt.% of Dolapix CE64, 8 wt.% of Pluronic and 5 wt.% of ethylene glycol. The ink exhibits pseudoplastic behaviour and optimal viscoelastic properties for printing. Transparent Y2O3 ceramics were characterized by mostly uniform dense microstructure with the presence of some large defects caused by the printing process. In-line transmittance of the obtained ceramics is 43 % in the range of 3–5 μm.

N. Almazova, S. Aubry, G. P. Tsironis

Ultrafast reaction processes take place when resonant features of nonlinear model systems are taken into account. In the targeted energy or electron transfer dimer model this is accomplished through the implementation of nonlinear oscillators with opposing types of nonlinearities, one attractive while the second repulsive. In the present work we show that this resonant behavior survives if we take into account the vibrational degrees of freedom as well. After giving a summary on the basic formalism of chemical reactions we show that resonant electron transfer can be assisted by vibrations. We find the condition for this efficient transfer and show that in the case of additional interaction with noise a distinct non-Arrhenius behavior develops that is markedly different from the usual Kramers-like activated transfer.

Niklas Manz, Yurij Holovatch, John Tyson

In this article we present and discuss the work and scientific legacy of Julian Hirniak, the Ukrainian chemist and physicist who published two articles in 1908 and 1911 about periodic chemical reactions. Over the last 110+ years, his theoretical work has often been cited favorably in connection with Alfred Lotka's theoretical model of an oscillating reaction system. Other authors have pointed out thermodynamic problems in Hirniak's reaction scheme. Based on English translations of his 1908 Ukrainian and 1911 German articles, we show that Hirniak's claim (that a cycle of inter-conversions of three chemical isomers in a closed reaction vessel can show damped periodic behavior) violates the \textit{Principle of Detailed Balance} (i.e., the Second Law of Thermodynamics), and that Hirniak was aware of this Principle. We also discuss his results in relation to Lotka's first model of damped oscillations in an open system of chemical reactions involving an auto-catalytic reaction operating far from equilibrium. Taking hints from both Hirniak and Lotka, we show that the mundane case of a kinase enzyme catalyzing the phosphorylation of a sugar can satisfy Hirniak's conditions for damped oscillations to its steady state flux (i.e., the Michaelis--Menten rate law), but that the oscillations are so highly damped as to be unobservable. Finally, we examine historical and factual misunderstandings related to Julian Hirniak and his publications.

Yujing Wei, Sibali Debnath, John L. Weber et al.

This study evaluates the precision of widely recognized quantum chemical methodologies, CCSD(T), DLPNO-CCSD(T) and localized ph-AFQMC, for determining the thermochemistry of main group elements. DLPNO-CCSD(T) and localized ph-AFQMC, which offer greater scalability compared to canonical CCSD(T), have emerged over the last decade as pivotal in producing precise benchmark chemical data. Our investigation includes closed-shell, neutral molecules, focusing on their heat of formation and atomization energy sourced from four specific small molecule datasets. Firstly, we selected molecules from the G2 and G3 datasets, noted for their reliable experimental heat of formation data. Additionally, we incorporate molecules from the W4-11 and W4-17 sets, which provide high-level theoretical reference values for atomization energy at 0 K. Our findings reveal that both DLPNO-CCSD(T) and ph-AFQMC methods are capable of achieving a root-mean-square deviation (RMSD) of less than 1 kcal/mol across the combined dataset, aligning with the threshold for chemical accuracy. Moreover, we make efforts to confine the maximum deviations within 2 kcal/mol, a degree of precision that significantly broadens the applicability of these methods in fields such as biology and materials science.